The invention relates to a plasma display panel comprising a transparent front plate and a rear plate that leave between them discharge spaces that are filled with a gas capable of emitting ultraviolet radiation owing to the effect of discharges, and the walls of which spaces are at least partly coated with a layer of a phosphor composition capable of emitting green, blue or red light, owing to the excitation of the said ultraviolet radiation.
Plasma panels for displaying images generally comprise two parallel plates provided with arrays of electrodes; the intersections between the electrodes of the various arrays define, between the plates, discharge spaces filled with discharge gas; when the panel is in operation, suitable voltages are applied between the electrodes in order to obtain light-emitting plasma discharges in these spaces; to separate these discharge spaces or groups of discharge spaces, an array of barrier ribs is generally placed between these plates, the said barrier ribs being intended to separate these spaces or groups of spaces and, in general, to separate these plates; to be able to emit visible light, although the discharges generally emit in the ultraviolet, layers of phosphors are generally placed on the walls of the cells, especially on the sides of the barrier ribs.
In trichrome plasma panels, there are three types of UV-excitable phosphors that emit in the three distinct primary colours, namely red, green and blue. Each cell of the panel is provided with only one type of phosphor and the cells are grouped together in groups of three adjacent cells of different emission colours, each group forming a pixel of the panel capable of displaying an element of each image to be displayed.
As red phosphor, it is known to use a composition based on an yttrium gadolinium borate doped with trivalent europium of general formula Eu:(YGd)BO3.
As green phosphor, it is known to use a composition based on manganese-doped zinc silicate of general formula Mn:Zn2SiO4.
As blue phosphor, it is known to use a composition based on a magnesium-barium aluminate doped with divalent europium of general formula Eu:BaMgAl10O17; such an aluminate is of the β-alumina type and has a spinel structure.
As illustrated in FIG. 10 of document US 2001-003410, the static charge of these various phosphors is very different:                +0.03 μC/g in the case of the gadolinium yttrium borate,        −0.15 μC/g in the case of the manganese-doped silicate,        +0.11 μC/g in the case of the magnesium-barium aluminate.        
As taught by document US 2001-003410, these differences in static charge characteristics result in fluctuations in the initiation and expansion of the discharges between the cells of different colours of a plasma panel, and this either requires expensive devices for compensating for these differences or results in defects in image display by the panel.
To partly remedy this drawback, document US 2001-003410 proposes mixing the green phosphor based on zinc silicate with another green phosphor based on a terbium-activated rare-earth borate.